Polishing disk



Jan. 3, 1939. P. w. DEMPsEY 2,142,182

IIIIIIIIIII SK Jan. 3, 1939. P. w. DEMPSEY POLISHING DISK Filed April 6, 1936 3 Sheets-Sheet 2 fig. 5

la lz INVEN-ron Fr-nLlF w DEMFSEY ATTORNEY Jan. 3, 1939. P. w DEMPSEY 2,142,182

POLI SHING DI SK Filed April 6, 1936 3 Sheets-Sheet 3 INVENTOR FHILIF WDEMF'SEY Patented Jan. 3, 1939 UNITED STATES POLISHING DISK Philip w. Dempsey, Pittsburgh, ra., assigner to The Westinghouse Air Brake Company, Wilmei-ding, Pa., a corporation of Pennsylvania Application April 6, 1936, Serial No. 72,853

6 Claims.

My invention relates to flexible polishing pads or backing disks for sheets of abrasive material, and method of making the same,

It has been well known to provide flexible disks of felt and like material as a backing structure for sheets of abrasive material for polishing at surfaces.

Many such backing disks are not sufficiently solid or rugged to withstand the strains placed upon them when run at high speed, and. such disks when operated at high speed tear out at the bolt holes through which theyere' attached to the flanged shaft on which they are mounted. Also the felt disks are expensive to manufacture.

An object of my invention is to provide exible backing disks for abrasive sheets and a method of making the same.

Another object of my invention is the provision of backing disks of the character described that are inexpensive to manufacture and are suf-A ficiently rugged and firm to be capable 'of use at high speed.

A further object of my invention is the pro'- vision of a disk of the character described formed of rubber reinforced with fabric and metal.

Other objects and advantages of my invention will be apparent from the following description,

of one preferred embodiment of a disk constructed in accordance with my invention, reference being had to the accompanying drawings, in

which Fig. 1 is a face view of a. finished flexible disk constructed in accordance with `my invention with a portion thereof broken away,

Fig. 2 is a sectional view taken from the line 2-2 of Fig. 1,

`Fig. 3 is a sectional view taken from the line 3--3 of Fig. 1,

Fig, 4 is an enlarged sectional view of a portion of the disk taken along the line 2-2 in mg- 1: v A Y Fig. 5 is a sectional view along the line 5-5 in Fig. 6, showing the built-up blank before being placed in the mold to be vulcanized,

Fig. 6 lis an exploded view showing the several layers of material from which the flange is constructed, separated from one another,

Fig. 7 is a perspective View of a roll of rubberized fabric material for insertion in openings provided therefor in the blank, and

Fig. 8 is a. sectional view of a. blank placed within a mold.

' Referring to the drawings, and more particularly to Figs. 1 and 2 thereof, I provide a disk for the purpose intended that overcomes the above objections of prior flexible disks, having a body portion l ofvulcanized rubber reinforced with fabric 2, having a metal disk core 3, that is provided with holes l extending through the metal center and body portion for accommodating bolts 5 by means of which the disk is attached to a suitable flange 6 of a driving shaft 1. A retaining member 8, shown broken away in Fig. 2, is also provided centrally of the disk and screw-V threadedly attached to the shaft 1.

Holes II) are also provided in the metal disk 3 and are centered between two bolt holes' 4 to accommodate rolls 9 (Fig. 7) of reinforcing materiai that extend `through the metal core and body portion Iof the disk.

The backing disk illustrated in Figs. 1 and 2, is made by the following process, the dimensions givin being illustrative merely of one specific embodiment.

Rubber compound is first rolled into sheets having the desired thickness of stock, for example, (1) stock having a thickness of .095 to .100";

(2) stock having a thickness` of .140" to .145;

rubber pressed into the interstices between the 9 strands of the fabric. This frictioning is done in such a way as to cover the fabric with as heavy a coat of rubber on both sides of the fabric as possible, the material being rolled until the thickness of the rubber compound coating of the fabric is within the specified limits. 'I'he materials thus prepared have a tacky surface, so that contacting surfaces adhere to one another as they are assembled, so as to form a blank that may be placed in a heated mold and pressed and curved into a finished disc.

To form the composite blank illustrated in Fig. 5 of say 9 inch external diameter, two circular blanks II and I2 in Fig. 6 are punched from the frictioned duck having 9 inch external diameters and, say, 2'1/8 inch internal diameters; four blanks, I3, I4, I5 and I6, are punched from the frictioned duck having 7 inch external and 2% inch internal diameters. Two blanks I1 and I8 are punched from the sheet of raw rubber compound stock that has been calendered to a thickness of from .095 inch to .100 inch, the blanks having an external diameter of 9 inches, and an internal diameter of '7 inches. One blank I9 is punched from the stock that has been calendered to a thickness of .140 inch to .145 inch, the blank having an external diameter of 9 inches and an internal diameter of 2% inches. One blank 2| is punched from the stock which has been calendered to a thickness of .155 inch to .160 inch, the blank having an outside diameter of 9 inches and an inside diameter of 21% inches.

In building up a composite blank, as shown in Fig. 5, the 9 inch external diameter blank II, and the inch external diameter blanks I3 and I 4 of frictioned duel: are placed together and rolled to remove any trapped air. Six holes are punched, centered around the central opening to line up with the bolt holes 4 in the metal ring 3 and of suicient diameter to accommodate the heads of the bolts as shown in Figs. 2 and 5. A like number of larger holes are equally spaced between the bolt holes to line up with the holes III in the metallic plate 3 to accommodate the reinforcing rolls of fabric material 9 when in final position.

The remaining 9 inch blank l2 and the two 'l inch blanks I5 and I8 of frictioned duck are now placed together and similarly rolled to remove any trapped air and are punched with holes corresponding to the holes I and I0 in the metal plate 3, the bolt holes in this case having a diameter sufllcient only to accommodate the shaft of the bolts 5 as shown in Figs. 2 and 5.

The metal disk 3 is then cleaned up by washing in benzol or similar cleaning liquid and given a coating of rubber cement. When the solvent in the rubber cement has evaporated the disk is then placed on the blank consisting of the three layers I2, I5 and I6, with the holes properly lined up with those punched in the fabric. The blank comprising the three layers of fabric I3, Il and II is then placed on the disk, the several layers being in the order shown in Fig. 6. The blank Il of rubber compound stock is then placed in position with the inner diameter thereof matching the outer diameter of the blanks I3 and Il, and in like manner the blank I8-is positioned so that its inner diameter matches the outer diameter of the blanks I5 and I5. The blanks I9 and 2l of rubber compound stock are then placed in position after holes corresponding to those in blanks II and I2, respectively, have been punched therein.

Six pieces or strips of material from the frictioned fabric are now cut, of such dimensions as to form rolls of sumcient diameter to illl the holes III, and of sufficient length to correspond with the width of the assembled composite blank as illustrated in Fig. 5. 'I'hese rolls are placed in the openings I0 in the composite blank, and the assembled composite blank inverted and placed in a hot mold comprising a base section 2|, as shown in Fig. 8, from which members 22 extend into the bolt holes. The mold cover section 23 is next placed in position, and the mold then placed in a proper press and allowed to vulcanize for twenty-five or thirty minutes at approximately fifty pounds steam pressure, at the end of which time the disk is removed from the mold to prevent an over cure. The edges of the disk and the bolt holes are trimmed and the disk is ready for use.

'I'he numerals used in Figs. 5 and 6 to identify the separate layers oi' raw material are applied to Figs. 3 and 4, to show the location of material in the finished disk, it being understood, however, that; upon vulcanizing, the individual layers of material lose their identity and become a composite whole.

It will be understood 4by those skilled in the art, that many modifications in the above described embodiment of my invention may be made without departing from the spirit of my invention, and I do not wish to be limited, otherwise than by the scope of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A flexible backing disk pad for abrasive sheets comprising a central metallic core disk to the opposite sides of which are formed a body vportion consisting of vulcanized rubber reinforced with fabric material, said body portion and metallic core disk having registered transverse openings therethrough in which are positioned rolled fabric reinforcing plugs.

2. A resilient backing disk for abrasive sheets comprising a central rigid core disk about which is formed a body portion consisting of layers of rubberized fabric and layers of rubber composition, said body portion and rigid core disk having registered transverse openings therethrough through which extend plugs oi.' rolled rubberized fabric.

3. A resilient backing disk for abrasive sheets comprising a central rigid core disk about which is formed a body portion consisting of layers oi' rubberized fabric on opposite sides of and adjacent said core disk, and layers of rubber composition adjacent said fabric, said body portion and rigid core disk having registered transverse openings therethrough through which extend plugs of rolled rubberized fabric.

4. A resilient backing disk for abrasive sheets comprising a central rigid core about which is formed a body portion consisting of layers oi' rubberized fabric on opposite sides of and adiacent said core and layers oi' rubber composition adjacent said fabric, the disk being provided with holes extending through the core and body portion through which may extend suitable supporting means for attaching the disk to a driving member.

5. In a resilient backing disk for abrasive sheets comprising a central rigid core disk about which is formed a body portion consisting of layers of rubberized fabric and layers of rubber composition, said body portion and core disk having registered transverse openings through which extend plugs of rolled rubberized fabric, said disk and body portion being also provided with holes extending therethrough through which may extend suitable supporting means for attaching the disk to a driving member.

6. In a device of the class described, a metallic reinforcing plate, rubberized fabric disks of substantially the diameter of the completed article at each face of said reinforcing plate, other rubberized fabric disks of smaller diameter than the completed article at the faces of the first named fabric disks, and rubber composition overlying said layers of fabric.

PHILIP W. DEMPSEY. 

